JPS5923582A - Gas waveguide laser generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a monolithic rod made of a galvanic material having a capillary tube formed therethrough, and a laser beam including the capillary tube.
The present invention relates to a gas waveguide laser generator with a capillary tube having only a gas-filled resonant cavity and high frequency electrical pumping means for inducing a laser discharge within the gas of the capillary tube.

The fields of application of such laser generators of the invention are diverse and can be used, for example, in medical and military applications.

Waveguide capillary lasers offer a significant advantage in volume over conventional lasers.

Advantages of their own are also obtained in terms of high-frequency excitation methods for inducing discharges in gas by generating an alternating electric field at a frequency in the range, for example, between 30 MH2 and J[Hz, preferably /θOMHz.

For example, the excitation voltage is low, eg, 10 θ, and concerns about insulation are no longer necessary.

The power source or pumping means can be downsized.

The service life is significantly increased because there are no anodes and cathodes to carry out the discharge and therefore no cathode potential drop due to decomposition of the laser gas.

The resonant cavity acts as a waveguide for the generated energy.

It should be pointed out here that transverse excitation, ie generation or application of a flowing electric field perpendicular to the longitudinal axis of the capillary tube, is preferred over longitudinal excitation.

one dielectric bar or block separates the other λ
The waveguide laser generator consists of two metal rods or blocks, a total of three rods or blocks form a chamber or waveguide with a rectangular cross section after assembly, and one metal rod does not act as an electrode. Already known.

It is advantageous to apply an insulating film or coating to the inner wall of each metal bar so that the excitation electric field cuts through this film layer, thereby avoiding oxidation of the metal bar by the laser gas. There is.

Furthermore, it is composed of a U-shaped part closed by a cover plate to fix the rectangular cross section, the U-shaped part and the cover plate are made of alumina, and a thin metal layer electrode is attached to the cover plate and the wall of the U-shaped part. Waveguide laser generators of the following construction are also known.Although these two types of waveguide lasers exhibit advantages as will be described below, they are not free from certain disadvantages.

That is, it is actually limited to a waveguide with a square cross section.

This geometry causes the energy distribution in the cross-section of the laser beam to have a regular appearance, ie a point-like distribution, which may result in several TE modes.

Furthermore, the structure of these lasers, whether it is a Sanderschich type structure or a cover plate type structure, is a so-called system L assembled with two or more blocks, so they are not free from assembly drawbacks. .

For example, from an optical point of view such lasers generate distortions and therefore also involve optical losses.

From an industrial manufacturing point of view, these known lasers are fitted with conditioning, brazing or gluing, which are almost never perfect.

Further, British Patent Application No. 20')/9041 describes a monolithic rod made of dielectric material and having capillary tubes formed therethrough. A gas waveguide laser generator is disclosed having a capillary tube and high frequency electrical pumping means for inducing a laser discharge within the capillary tube.

Due to the monolithic nature of this waveguide, all the drawbacks associated with gas pipes produced by known assembly are eliminated.

However, the generator disclosed in the above-mentioned British patent application has electrodes that penetrate into the capillary tube, and these electrodes are therefore oxidized by the decomposing laser gas and
This shortens the useful life of the laser. This phenomenon is also caused by the attack (sputtering) of these electrodes during electrodynamics.

The aim of the invention is to obviate the drawbacks mentioned directly above.

llL]” Sae.

1j above, the present invention comprises a monolithic rod made of dielectric material to form a capillary tube therethrough, a resonant cavity L containing the capillary tube and filled with laser gas, and a blazer in the gas of the capillary tube. In a gas waveguide laser generator comprising a capillary tube with high frequency electrical pumping means for inducing an electrical discharge, said rod has an intermediate portion within a four-sided relationship with said capillary tube, and said rod has a thin walled portion of said rod. The present invention relates to a gas conduit laser generator characterized in that electrodes are provided on both sides of the capillary tube over its entire length.

In a clever embodiment of the laser generator of the invention, the pumping means excites the laser gas with radio frequency.

In this case, the impedance of the plasma is positive and therefore the plasma is homogeneous.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION The invention will be more clearly understood from the following description, taken in conjunction with the accompanying drawings.

Referring to the drawings, the illustrated gas waveguide laser generator is
A monolithic bar made of a dielectric material such as BeO, A4203, etc. and having 11 capillary tubes.
A resonant cavity 6 is formed within the envelope 3 by the two mirrors, and has a jacket or envelope 3L closed at both ends by four mirrors y and the left side. The rod/is located within a resonant cavity and contains a working gas.

Is the external form of a monolithic rod roughly axial? It has a cylindrical shape. This monolithic rod l has a cylindrical end portion 7 and g and a parallel plane 10 equidistantly spaced from the axis of the shaft and connected to the two end portions 7 and g. and/or has a thinned intermediate portion 7.2 defined by and//. Just as an example, the length of the rod made in this way is 2.
The diameter is 30 mm, the diameter is 20 mm, the groove at the center is approximately J, J, and the axial length is 3 mm at the end.

In the illustrated embodiment, the capillary tube has an axially circular cross section. Note that the capillary tube has a diameter of −,! ;mm
Formed as. The capillary tube a extends from one end of the rod l to the other end, and opens into the cavity B at both ends.

The rod / is attached to the envelope 3 in still tangential relation to the inner wall of the envelope 3 by one current ring 13 and /41.
held within. Disposed within the annular ring are respective end portions 7 and g of the rods, which serve to hold and center the rods.

Rings /3 and /3 are drilled with orifices for circulating laser gas from the outside of the rod to the inside and vice versa.

Although two flat mirrors are shown in FIG. 1, the present invention does not preclude the use of other mirrors, such as spherical mirrors. Note that one of the λ mirrors is
It is a translucent plate to extract the laser beam.

The gaseous medium used at pressures on the order of 0 to 100 Torr, in the illustrated example, consists of a mixture of carbon dioxide gas, nitrogen and helium, and upon excitation produces infrared radiation at a wavelength of about 70° and 4 μm. Generates emissions.

However, the present invention, for example, still! This does not preclude the use of other gaseous media, such as mixtures containing carbon monoxide, which emit infrared radiation at wavelengths of /1 m.

The waveguide laser generator described here uses electrical pumping and therefore requires a power source (not shown).
and λ electrodes arranged to cause an electrical discharge in the gas wool tube III.

The laser is pumped at high frequencies, particularly radio frequency RF. This bombing provides the advantages mentioned above. The excitation or excitation is a high value alternating transverse electric field (TE), i.e. axial? Preferably, lateral excitation is achieved by generating an alternating electric field in a direction perpendicular to the direction.

However, it should be noted that the invention may also be implemented with longitudinal RF excitation along axis 7. However, in this case some lateral excitation will also be induced.

Electrodes, each connected to one terminal of AC 7M and TAX, are arranged on the two flat surfaces 10 and // of the middle part of the rod.

The first electrode 16 is in the form of a thin line and extends over the entire length of the dowel portion /2, and is connected to the other grounded reference electrode /7 to which, for example, a radio frequency excitation potential is applied. The radiator extends almost the entire length of the radiator, but has a relatively large width, and also functions as a radiator.

According to the embodiments of the invention described above, the zero gas tube has a monolithic off '1' construction, which offers significant advantages over and above the advantages of the known gas waveguide lasers with radio frequency excitation. and all the disadvantages of the service pipes of the assembled structure are eliminated.

The thin-walled central portion of the rod in which the m-wave capillary is formed increases the volume of the envelope that can accommodate the laser gas and through which it can circulate. Renewal of the gas in the capillary tube therefore takes place in a very satisfactory manner.

π1. has a very simple structure. The pole acts over the excited or excited capillary region, making it possible to obtain a homogeneous laser plasma. The waveguide has a circular cross section, which is the optimum condition from an optical point of view. , and laser emission is achieved in a mode with a Gaussian energy distribution centered on axis 9.

This capillary configuration is in fact obtained, in particular, by the manufacturing method described below.O. In practice, it is impossible to form capillaries in rods of excessively fine structure.

A capillary Ω is realized by forming an axial through hole in the rod by drilling an annular hole. It should be noted that the manufacturing costs of such capillaries are very small. Of course, the capillary does not have to be axial. The above rod is then machined into λ planes IO and l.
The central section along / is thinned to be substantially coplanar or parallel to the capillary λ, and one cylindrical section at one end.

Provide for centering and holding purposes. the result,
The wall thickness of the fracture/in the central part/2 is substantially 0.1
You can obtain a structure that does not exceed your friends. Of course, the bar can also be thinned along other planes than the flat surface.

Next, in a known manner, the top plane 1 of the Isogura-processed area is
The two electrodes //) and /7 are placed on top of 0 and //.

Although the above description has been made in relation to a cylindrical rod for simplicity, it goes without saying that rods of different shapes may be used.

Additionally, extrusion manufacturing methods can be carried out using tools that are complementary in shape to the capillary tube. In this case, the advantage is that the capillary tube can be made with any cross-sectional shape, such as, for example, circular, square or rectangular. However, it is practically impossible to obtain a cylindrical capillary tube using the assembly method.

According to the rectangular cross-section capillary tube, the gl'J multi-passage technique can be advantageously realized, and an additional opaque mirror can be placed between the end mirrors of the waveguide and the resonant cavity to improve the inside of the waveguide. It is possible to obtain several laser beam paths in the width direction. For example, each fi is placed near one end of the waveguide.
Three paths are obtained with an additional mirror of f.

[Brief explanation of drawings]

FIG. 1 is an axial cross-sectional view of a laser generator according to the present invention;
2 is a cross-sectional view of the waveguide taken along line II-II in FIG. 1, FIG. 3 is a plan view of the bar-shaped waveguide portion of the laser generator in FIG. 2 is a plan view of the rod-shaped waveguide portion of the laser generator of FIG. 1 viewed from the other side. FIG. /...rod, ko...penetration waveguide, 3...envelope, ! ...Mirror, B...Resonance cavity, 7, G...Centering part, ?・・Axis line, /, 3. /'I... Annular ring, 1
5・War orifice, /A・・TfL pole, /7・・Reference electrode 0

Claims (1)

[Claims] /) a monolithic rod made of a dielectric material and having a capillary tube formed therethrough; a resonant cavity containing the capillary tube and filled with laser gas; a gas waveguide laser generator comprising a capillary tube with high-frequency electric pumping means for inducing an electric discharge, the rod having a thin-walled intermediate portion in coplanar relationship with the capillary tube;
A gas waveguide laser generator characterized in that electrodes are provided on both sides of the capillary tube over the entire length of the thin section of the rod. , 2) A gas waveguide generator according to claim 7, wherein seven of the electrodes are in the form of a thin wire and the other electrode is in the form of a strip. 3) A gas waveguide laser generator as claimed in claim 1, wherein the rod has λ end portions for extending and maintaining the rod within an envelope defining a cavity. Patent MP where the gas contains carbon dioxide gas! The gas waveguide laser generator described in item 1 below. , t) A gas waveguide laser generator as claimed in claim 1, wherein the pumping means excites the laser gas at radio frequencies. A) A gas waveguide laser generator according to claim 1, wherein the capillary tube has a circular cross section.